Self-cleaning hot-blast stove.



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SELF CLEANING HOT BLAST'STUVE.

(Application led Har. 29,'-1901,)

2 Sheets-Sheet 2.

(No Model.)

|NVENTFL JWCabot,

/ITNEEE E5 l ATTUHNEY;

PATENT OFFICE.

JOI-IN NV. CABOT, OF .IOI'INSTOWN, PENNSYLVANIA.

SELF-CLEANING HOT-BLAST STOVE.

SPECIFICATION forming part of Letters Patent No. 710,748, dated October '7, 1902.

Application tiled March 29. 1901. Serial No. 53,540. (No model.)

To all whom, t Wtcty concern:

Be it known that I, JOHN W. CABOT, a citizen of the United States, and a resident of Johnstown, in the county of Cambria and State of Pennsylvania, have made a certain new and useful Invention in Self-Cleaning Hot-Blast Stoves; and I declare the following to be a full, clear, and exact description of the same, such as will enable others skilled in the art to which it appertains to make and use the invention, reference being had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification.

The invention relates to blast-furnaces, and it consists in the novel construction and combinations of parts comprising a hot-blast stove designed for use in connection with a blast-furnace, as hereinafter setforth.

The operation of an ordinary hot-blast stove, briefly described, is as follows: Gas from the top of the furnace is admitted to the stove through the gas-valve and is burned in one of the vertical flues, made much larger than the remainder of such iiues and called the combustion-chamber,7 by means of air admitted through the air-valves. The products of combustion go up to the top of the stove, turn,and passing down through the other flues in the regenerative part of the brickwork escape through the chimney-valve to the chimney. After a suitable time the gas-supply is shut off, the gas, air, and chimney valve are closed, and cold blast is introduced through the cold-blast valve, which is located near the chimney-valve. The hot-blast Valve, con-v nected with the hot-blast main, is opened, and the cold blast is thus caused to flow through the stove in the opposite direction to that of the gases used in heating up the stove and passes out of the stove into the hot-blast main. lVhile the blast is being heated in this manner the gas-supply has in the manner above described been turned into a second hot-blast stove in order to heat it up ready for use when the heat in the first one becomes exhausted. In this manner the operation of heating the blast goes on continuously.

The above-described waste gases from blastfurnaces carry over with them large quantities of dust, small particles of ore, coke, and iiuX, especially when the furnace is using the iinerores,in which sometimes twenty per cent'. of the ore is fine enough to pass a one-hundredmesh sieve as well as a large amount of very fine solid material called fume This material is sometimes called collectively fluedust. It has a very load effect upon the operation and duration of life of the stoves, as it lodges in all parts of the iiues and brickwork, clogs up the valves,cuts the valve-seats, makes trouble with the joints, and causes the various parts of the apparatus to leak, tbc. The finest portion of it formsacoating on the surface of the bricks and on the iiues and soon reduces the efficiency of stoves until it becomes necessary to take them out of service to allow them to cool down for a number of days until cool enough for nien to get into them, when the accumulation of dust and dirt is scraped out and the fines, brickwork, valves, ttc., are brushed oif by hand. This work is laborious, unsatisfactory, and expensive, and, moreover, the stoves and the brick linings are injured by these periodical successive coolings and heatings. In my new and improved' form of hot-blast stove these evils are designed to be avoided, the stove is cleaned and kept free from accumulation of tine-dust without coolingr it down and while it is in operation without the employment of hand -labor or any special appliances, the cleaning being done by the use of the blast itself.

A description of my self-cleaning hotblast stove follows.

Reference is made to the drawings,illustrat ing a metal-cased iire-brick-lined two-pass stove, in which like letters refer to like parts.

Figure l is a vertical section of the stove upon the line l l, Fig. 3; Fig. 2a horizontal section onthe line 2 2, Fig. l; and Fig. 3 is a horizontal section on the line 3 3, Fig. l.

D is a combustion-chamber. E a partition dividing the regenerator into two equal compartments F and F. This partition extends to the bottom of the stove, but not to the top. The open space N on the top of the regenerator is common to both compartments of the regenerator and to the combustion-chamber D. The space H at the bottom connects the fines f in the compartment F of the regenerator through the opening I, the iiue or passage-way J through the quick-opening valve K, and the chimney-valve L with the chimney M. In a similar manner the corresponding space H' under the regenerator-compartment F' and separated from the space H by the partition E connects the dues of regenerator-compartment F' with the passage-way J' to the chimney M. O is a cold-blast valve in a branch of the passage-way J, connecting the compartment F with the cold-blast main P. O' is a similar valve in a branch of the passage J', connecting the compartment F' with the cold-blast main P.

Q is a gas-valve for admission of gas to the combustion-chamber D.

R is au air-valve for admitting the air needed for burning the gas.

Sis a hot-blast valve for regulating the exit of the heated blast to the hot-blast maiu T.

I do not confine myself to the use of two compartments only in the regenerator, but may also use three or more compartments. The regenerator F F' may be divided into three or more such checker-filled compartments by building in two or more dividingpartitions exactly like the partition E, adding a passage-way or branch J for each compartment so provided.

Having described my apparatus, I will now describe how it is operated. After the stove has been on gas for the usual period the gas-valve, the air-valves, the quick-opening relief-valve K and K', and the chimney-valve L being open and the hot-blast valve S and the cold-blast valves O and O' being closed and it is desired to clean the stove or blow it-that is to say, to blow out the flue-dust that has accumulated during the heating-up period before putting the stove on blast the order of procedure is as follows: Shut off the supply of gas by closing the gas-valve Q. Close both quick-opening relief-valves K and K', leaving the chimney-valve open. Open the cold-blast valve O, which connects the supply of cold blast in the cold-blast main P with the passage J. This has the eect of filling the stove with blast at the pressure existing in the cold-blast main. The exit of any blast is prevented because the hot-blast valve is closed. Now the quick-opening relief-valve K', connecting the chimney with the passage J and the regenerator-compartment F', is suddenly opened for an instant, when the pressure of air in the stove coming from the cold-blast main through the valve O rushes up through the dues fin the compartment F, crosses over on the space N and down through the corresponding fines in the compartment F', and out of the chimney through the quick-opening relief-valve K' andthechimney-valveL. Thesudden puit or rush of air under a high pressure and at a great velocity due to the whole current being forced to rush through one-half of the regenerator-Iiues contained in one compartment of the regeneratcr F and then through the iiues in F" dislodges all of the dust or fume which has accumulated in the stove.

This puing of the stove may be repeated as often as desired by suddenly opening and as quickly closing the relief-valve K'. In order to clean off any dirt which may adhere in a stalagmitic form, the rush of air may be reversed and caused toasceud the iiues in the compartment F and go down through F and out at the chimney by reversing the order of procedure and first opening the cold-blast valve O' (the valve O in this case being closed) and then the quick-relief valve K. This reversing of the direction of the blow by the above-described manipulation of the valves may be repeated until both the regenerator-compartments F and F' are thoroughly cleaned.

In case the regenerator is divided into more than two compartments the method of cleaning each compartment is similar to the abovedescribed process, the stove being lled with blast under pressure by opening the valve connecting any one compartment with the supply of blast and then suddenly opening the branch relief-valve connecting any other compartment with the chimney.

hat I claim as new, and desire to secure Letters Patent for, is as follows:

l. A hot-blast stove, comprising a metallic casing, a chimney, a lire-brick lining, a combustion-chamber with gas and air valves, a cold-blast main, a hot-blast valve, a regenerator divided into two or more compartments, separated at the bottom, and separately connected at the bottom by valved passage-ways to said chimney, and by valved passage-ways to the cold-blast main, substantially as specified.

2. In ahot-blaststove,the combination with a combustion-chamber, its gas and air valves, a cold-blast main, and a valved chimney, of

va regenerator divided into a plurality of compartmentscommunicatingat the top and separated at the bottom, and a separate valved communication between each compartment and the valved chimney, and between each -compartment and the cold-blast main, substantially as specified.

3. A two-pass hot-blast stove having regencrater-compartments, a valved chimney, a hot-blast valve, means for causing a pu blast of air to blow out accumulated dust and fume from the stove, and means for reversing such puff blast, substantially as specified.

Ll.. In a two-pass hot-blast stove, the combination of one combustion-chamber with a plurality of checker-filled compartments placed side by side, communicating at top and separated at bottom, a valved chimney, a coldblast main, separate passage-ways from each compartment to said chimney and cold-blast main, and means for causing a blast puft` of air from said cold-blast main through the stove to said chimney, substantially as Specified.

5. A hot-blast stove, consisting of a cylindrical shell, having a fire-brick lining, and provided with a combustion-chamber, a re- IOO IIO

generator divided into two or more compartments communicating at one end thereof and separated at the other end thereof, a hot-blztst valve, a coldblast mein, a valt-'ed chimney, and separate passage-Ways leading from the separated ends of each compartment to said chimney and to seid cold-blast main, and valvular means in seid passage-Ways for effecting a puff blast of air from said cold-blast main through the stove to said chimney for cleaning purposes, substantially as specifi ed.

6. In :t hot-blast stove, having two or more regencritter-compartments, and :t cold-blast main, means for causing a pui of air through 

